1. Field of the Invention
This invention relates to an aqueous ink which contains a water-insoluble coloring material, and an ink set having the same. More particularly, it relates to an aqueous ink which is preferable in an ink-jet recording processes, and to an image-forming method which make use of the aqueous ink.
2. Description of Related Art
Conventionally, inks which contain a water-insoluble coloring material such as pigments as colorants (pigment inks) are known to give images having good fastness such as water resistance or light-resistance. In recent years, various techniques are proposed for the purpose of more improving the image density of images formed using such inks.
For example, as disclosed in Japanese Patent Application Laid-open No. 2000-198955, it is proposed to achieve much more improvement in image density by the use of an ink containing a self-dispersion type carbon black and a specific salt. As also disclosed in Japanese Patent Application Laid-open No. 2000-63719, a technique is proposed in which an ink-jet recording ink which is a composition containing a pigment, fine polymer particles, a water-soluble organic solvent and water and an aqueous solution containing a polyvalent metal salt are caused to adhere to a recording medium, and the ink composition is allowed to react with the aqueous polyvalent metal salt solution to form images having a high grade. In these techniques, in both cases, the pigment present in the ink in a dispersed state is forcedly made to flocculate on the recording medium surface to thereby keep the pigment from permeating into the recording medium, to obtain images having a much higher density.